Answer:
3/8
Step-by-step explanation:
Find the height of the trapezoids
20 - 10 = 10
10/2 = 5
Find the area of the trapezoids
5*(20+10)/2 = 75
The formula for the area of the trapezoid is the height * the bases added together divided by 2
75*2(this is because there are 2 trapezoids) = 150
Put this to proportion of the total area of the dart board
150/[tex]20^{2}[/tex] = 150/400 = 3/8
3/8 is the probability that you score 3 points
